Err..

1) How many years has Nokia been in the cell phone market compared to Apple and Google.

2) How many years have they been in the smartphone market compared to Apple and Google?

3) How fast are Apple and Google growing?

Just because Rome was on top before doesn't mean they'll be on top forever. [Though I don't see Apple being on top either, they're the type that would rather own their own market and be content with that since they can never capture the entire market with their tactics].

My concern more with compatibility breaks with the OS and device releases will be how long the n900 is supported. It would be terrible if the lifespan of the device was only one or two years. Especially if Nokia pulls stunts like "fixed in freemantle" if the fix could also be done on the previous OS. But hopefully being built on an open-source community will ensure a long life to re-coup the 600 dollar investment into the device.